Kneading apparatus



m .1 2 m 6 h 3 q 1I. .mw 2 e e v.n S.. 2 L A T EMR Uma Gu im .1 WF s Nov. 8, 1938.

Nov; 8,'1938. s. KlEssKAL'r E-r AL 2,135,264 I KNEADING PPARATUS Flled July 3 1936 5 2 Sheets-Sheet 2 u u sz s' z a 1 z `1 l. iu -ol I v l l l.

Patented Nov. 8, 1938 UNITED STATES KNEADING APPARATUS Siegfried Kiesskalt, Hans Tampke, Ernst Weingaertner, and Karl Winnacker, Frankfort-onthe-Main, Germany, asslgnors to I. G. Farbenindustrie Aktiengesellschaft, Frankfort-on-tlie- Main, Germany Application July 3, 1936, Serial No. 88,902 In Germany July 25, 1935 5 Claims. (Cl. 259-104) 'I'he present invention relates to an improved apparatus for preparatory processes, such as mixing or kneading.

Certain preparatory processes are applied to masses which are in a plastic condition, for instance, plastic masses of the ceramic and rubber industries and masses occurring in the known processes of making dispersions of coal and oil free from ash, so-called flowing coal, and the like. These processes involve kneading, mixing and, in part, washing operations, the masses having in most cases to be subdivided once or several times during the operation in order to create a large surface. Besides a continuous passage, the possibility of a treatment in stages and application vofthe counter-current principle are desirable.

The present invention provides an apparatus which may be used with advantage in such preparatory processes. 'I'his apparatus comprises a right-handed worm and a left-handed worm arranged so that their threads lntermesh. The

thread of each worm is in axial direction narrow at one end relatively to the pitch of the worm and increases in cross-section towards the other end until the intermeshing threads engage so closely that in combination with a casing surrounding the worms at this end they constitute a valveless pump. This means that -at the end of the worm the cross-section of the thread remains constant' during at least one turn. Owing `to the increasing cross-section ofthe threads,

there is provided a passage whose cross-section decreases in the axial direction of the worms from one end (the inlet end) of the apparatus to the other end (the outlet end). Several such pairs of worms may be connected in series with intercalation of'perforated press plates. The apparatus may also be provided with means which allow a counter-current operation with treating liquids. For this purpose there may be provided means for introducing treating liquid into the casing adjacent to the discharge outlets and means for discharging treating liquid `adjacent to the inlet end of the casing whereby the material being treated and the treating liquid pass through the casing in counter-current to each other.

The apparatus of this invention, therefore, may be an organic combination of twin screw conveyors and valveless pumps with passages of changing volume.

The accompanying drawings diagrammatically illustrate the invention.

Fig.V 1 is a right-handed worm, the corresponding left-handed worm having the same prole structure.

Fig. 2 is a right-handed worm and a lefthanded worm arranged axially,

Fig. 3 is a section through these two worms at the inlet end and Fig. 4 is a section near the outlet end,

Fig. 5 is an arrangement in series of several pairs of worms.

m-m is the axis ofthe worm A; a1 az as a4 as as is the helicoidal centre line of the worm threads of the constant pitch a1 as or a2 a4. 'I'he form illustrated may be supposed to be derived from a square-threaded worm with threads of rectangular profile, the initial width of the thread being equal to half the pitch. On the left hand side of the drawings the limits are indicated by broken lines b4' c4' be ce following b2 c2. b1 b: cz c1 show half a thread which remains in the original form, as' it is required in this form for the valveless pump-like closing at the pressure end. From b2 c2 onwards the upper and lower `helicoidal surfaces have a wedge shaped form so them has a constant pitch. Such worms may be made in a simple manner by tapering the threads with the aid of inclined milling cutter discs. The cross-section of the upper part of the threads (b1. c1, b2, c2) does no longer increase, that is to say the distance from b1 to c1 is equivalent to the distance from b2 to a. If the cross-section of the thread is kept constant in this manner for at least one turn, several worms of this kind situated parallel to each other form valveless pumps at the parts where the threads have a constant cross-section. v

As shown in Fig. 2 such a right-handed worm S1 is now assembled with a left-handed worm Sz made in exactly the same way. When the worm S1 rotates counter-clockwise and the worm Sz clockwise, it is apparent that the narrow threads act on the mass of material at the inlet end I of' be given the form of an open trough having a hopper Q (see Fig. 3) but at the outlet II it will have the form of acasing surrounding the worms (see Fig. 4). In order to better distinguish the single parts a small space is shown between the gears s1 and s2 and the casing P. This space does not really exist as otherwise the chambers between the threads of the worm would not be completely separated from each other and a valveless pump would not be formed-with the casing. The operation of this pair of worms, according to the invention, is as follows:

The quantity of the mass taken up by the screw threads in the region I is considerably Consequently the casing-P at the inlet I will generally' larger than that contained by the worms at the outlet II, which has the form oi' a pump. Consequently, only part of the mass taken up at I will enter the nal threads at II; the other part is more and more forced back to I by the screw threads which do not engage closely at the inlet and is thereby kneaded. A circulation of a part of the mass is thus introduced in a direction parallel with and opposite to the conveying current determined by the dimensions of the end of the worm.

The' assembly of the whole device is illustrated in Fig. 5. On the two continuous lines of shafting W1 W2, which are coupled by means of toothed wheels Z1 Z2, several successive pairs of worms Si S2 are arranged, those of each pair being engaged in the manner indicated in Fig. 2.

-The drawings show, for instance, a three-stage construction, but it is also possible to use one pair only or more than three. Between each of the consecutive pairs of worms a press plate R. is inserted which has openings of the desired cross section. The mass to be treated is pressed through these openings by the pump portion of the pair of worms and then enters between the conveyer portion of the following pair of worms. The mass introduced through the rst hopper Q is treated, as represented in Fig. 5, in three stages and is pressed or pumped out of the apparatus by the last pair of worms at T. In the case shown there is provision for causing a treating liquid to travel in counter current to the material. The conduit v1 is introduced near the discharge outlet of the next to last casing. From this part the conduit v: leads to the corresponding part of the preceding casing and from there a third conduit v3 leads to the inlet end of the entire apparatus. 'Ihrough these conduits v1, vz and va the liquid for treating is passed through the entire device whereby a part of the liquid during the kneading operation is taken along by the worms and conducted together with the mass to be kneaded whereas the excess of the liquid leaves the apparatus at U.

The eirect of the worms providedwith a fiat or a broad passage may be enhanced by using not only threads with a converging or tapered profile, but by cutting the worms with a pitch which becomes smaller from-the inlet end to the outlet end. Moreover, at the pumping end the threads may be given an additional proile in any known manner in order to improve the pumping action. Finally at the conveying end the worms may be perforated in order to improve the kneading action. 'I'he arrangement of the worms may also be used alone as a kneader with conveying action. The principal advantage of the invention over blade kneaders and mixing worms, lies in the possibility of combining mixing, kneading by displacing action and mere pumping action in one and the same device.

We claim:-

1. A kneading apparatus comprising a casing, right-handed and left-handed worms arranged in the casing so that the threads of the worms intermesh, the threads of the worms being of constant pitch, the cross-sectional area of the threads of each worm gradually increasing from the inlet to the outlet end of the casing. whereby the threads of the worms are relatively widely separated at the inlet end and closely spaced at the outlet end, the worms and casing forming a valveless pump at the outlet end of the casing.

2.` A kneading apparatus comprising a casing. a right-handed and a left-handed worm arranged axially in the casingso that the threads of the worms intermesh, the threads of the worms being of constant pitch, kthe cross-sectional area of the threads of each worm gradually increasing from the inlet end to the outlet end of the casing whereby the threads of the worms are relatively widely separated at the inlet end and closely spaced at the outlet end to provide a passage of decreasing volume from the inlet point to the outlet point, the worms and casing forming a valveless pumpI at the outlet end of the casing.

3. A kneading apparatus comprising a casing', several pairs of right-handed and left-handed Worms arranged axially in series in the casing so that the threads of each pair of worms intermesh, the threads of the worms of each pair being of constant pitch, the cross-sectional area of the threads of each worm gradually increasing from the inlet end to the outlet end of the casing whereby the threads ofthe worms are relatively widely separated at the inlet end and closely spaced at the outlet end of each pair to provide a passage of decreasing volume from the inlet point to the outlet point, the worms and the casing forming a valveless pump at the outlet end of each pair of Worms.

4. A kneading apparatus comprising a casing. several pairs of right-handed and left-handed worms arranged axially in series in the casing so that the threads of each pair of worms intermesh, perforated press plates interposed between each pair of worms, the threads of the worms of each pair being of constant pitch, the crosssectional area of the thread of each worm gradually increasing from the inlet end to the outlet end of the casing whereby the threads oi' the worms are relatively widely separated at the inlet end and closely spaced at the outlet end of each pair to provide a passage of decreasing volume from the inlet point to the outlet point, the worms and casing forming a valveless pump at the outlet end of each pair of worms.

5. A kneading apparatus comprising a casing, several pairs of right-handed and left-handed worms arranged axially in series in the casing so that the ,threads of each pair of worms intermesh, an inlet for material to be treated at one vend of the casing and a discharge outlet for treated material at the opposite end of the casing, perforated press plates interposed between each pair of worms, the threads of the worms of each pair being of constant pitch, the cross-sectional area of the thread of each worm gradually increasing from the inlet end to the outlet end of the casing whereby the threads of the worms are relatively widely separated at the inlet end and closely spaced at the outlet end of each pair to provide a passage of decreasing volume from the inlet point to the outlet point, the worms and casing forming a valveless pump at the outlet of each pair -of Worx is and means for introducingr treatingliquid into said casing adjacent to said discharge outlets and means for discharging treating liquid'adjacent to the inlet end of the casing whereby the material being treated and the treating liquid pass through the casing in counter-current to each other.

SIEGFRIED KIESSKALT.

HANS TAMPKE.

ERNST WEINGAERTNER.

KARL- WINNACKER. 

